A transmission channel single-chip integration technology is conducive to microwave point-to-point equipment developing towards a direction of high frequency, high integration level, low cost and low power consumption. However, due to semiconductor technologies, comparing a device adopting the transmission channel single-chip integration with an independent single-function device, a linear output power level of the transmission channel of the device adopting the transmission channel single-chip integration may be reduced. In order to keep the same output power with the conventional single-function device, a linearization process needs to be performed on the device adopting the transmission channel single-chip integration.
A predistortion (predistortion) technology is an implementation manner of linearization. Nonlinear distortion exists in the device adopting the transmission channel single-chip integration. An operating principle of the predistortion technology is to superpose distortion opposite to the nonlinear distortion of the device onto the input signal, so as to counteract the nonlinear distortion of the device. The distortion opposite to the nonlinear distortion of the device can be obtained according to a nonlinear distortion characteristic of a power amplifier. Digital baseband predistortion is a relatively widely applied predistortion technology. In an existing digital baseband predistortion system, a feedback channel is implemented by a super-heterodyne receiver.
The prior art at least has the following problems.
A digital baseband predistortion system adopting a super-heterodyne down-conversion structure means to add a receiving channel. What is fed back by a super-heterodyne receiver is an output signal of a power amplifier. In a microwave system, a carrier frequency of the output signal of the power amplifier is high, considering existing semiconductor technologies, for application in a high carrier frequency condition, an implementation structure of the super-heterodyne receiver adopted by the feedback channel is complex, and a hardware cost is high. In addition, due to complex frequency components of the super-heterodyne receiver itself, in order to shield internal signal leakage in the super-heterodyne receiver, the implementation structure is more complex. Therefore, the feedback channel is difficult to be integrated onto a single-chip together with the transmission channel.